JP2975438B2 - Pneumatic tire - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire capable of reducing vibration noise of a tire vibrated due to a tread pattern, road surface unevenness, etc., and improving quietness during running.

[0002]

2. Description of the Related Art In recent years, there has been a strong demand for low noise and quietness of vehicles, and for that purpose, it is necessary to reduce tire noise due to rolling.

[0003] The noise caused by the tire includes, in addition to the air pumping sound based on the air column resonance in the tread groove, the vibration sound of the tire caused by the tread pattern, the unevenness of the road surface, and the vibration sound. A tire ring internal resonance sound or the like in which the air inside the tire resonates is known. In particular, the vibration sound and the ring internal resonance sound are transmitted to a vehicle and become muffled sounds in the vehicle, and the influence thereof is extremely large. It should be noted that such vibration noise and the like are caused by the fact that the impact on the tread surface caused by the unevenness of the road surface during the rolling of the tire causes the sidewall portion to vibrate using the carcass as a transmission medium, and the frequency of the vibration is the natural vibration of the tire. When the numbers match, the noise level increases rapidly.

Therefore, conventionally, the tread rigidity is reduced in order to reduce such vibration noise and the like, and the impact of the tread at the time of grounding is reduced. Also, as disclosed in Japanese Patent Application Laid-Open No. 63-154410, for example, A structure in which a sound absorbing layer made of a foamable rubber material is provided on the inner surface of the tire cavity has been proposed.

[0005]

However, the one that reduces the tread rigidity causes a decrease in the steering stability and the like, such as impairing the cornering force.
No. 4410 discloses that an inner liner is provided between a carcass, which is a transmission medium, and a sound absorbing layer, although vibration in a sidewall portion can be suppressed from being transmitted to a tire cavity to reduce annular internal resonance. Since the layer is interposed, the effect of suppressing the vibration of the sidewall portion itself is poor, and the noise reduction effect as a whole is insufficient.

The present invention is based on the provision of a sound absorbing layer between the carcass and the inner liner layer. The vibration of the sidewall portion itself can be reduced while maintaining the effect of suppressing the ring internal resonance, and the low noise of the tire is achieved. The purpose of the present invention is to provide a pneumatic tire that can achieve the realization.

[0007]

In order to achieve the above object, a pneumatic tire according to the present invention is provided with a carcass which is turned around a bead core of a bead portion from a tread portion to a sidewall portion and surrounds a tire cavity. An inner liner layer located inside the carcass and continuously disposed facing the tire cavity, and a sound absorbing layer disposed between the inner liner layer and the carcass and disposed on a sidewall portion. In addition, the sound absorbing layer is formed of a porous material having closed cells having a cell diameter of 0.01 cm or less.

[0008]

In the pneumatic tire according to the present invention, the sound absorbing layer is formed in contact with the carcass serving as a transmission medium of the tire vibration, so that the vibration of the carcass ply itself is directly absorbed and reduced. The vibration noise at the side wall portion can be effectively reduced.

Moreover, the sound absorbing layer can also prevent the propagation of carcass vibration into the tire cavity, and is also useful for suppressing annular internal resonance. In addition, since the sound absorbing layer is covered with the inner liner layer, it is not deteriorated by moisture or the like contained in the filling air, so that the durability of the tire can be maintained, and only the side wall portion where vibration occurs is provided. Since it is provided, an increase in tire weight can be reduced.

[0010]

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1 showing a state where the rim is assembled to the regular rim R, the pneumatic tire 1 includes a pair of bead portions 3 each having a bead core 2, a sidewall portion 4 extending radially outward from each bead portion 3, It has a toroidal shape having a tread pattern on the outer surface and a tread portion 5 connecting between the outer ends of the sidewall portions 4, and an air-filling cavity H is formed between the regular rim R and the regular rim R. Is done.

Also, between the bead portions 3, a fold that is turned from the inside of the tire to the outside around the bead core at both ends of the main body portion 7A extending from the tread portion 5 to the bead portion 3 through the sidewall portion 4. A carcass 7 provided with a portion 7B is bridged, and a tough belt layer 9 is wound around the carcass 7 radially outward and inside the tread portion 5.

The carcass 7, in this embodiment, is formed of at least one steel carcass cord 7a arranged at an angle of 75 to 90 degrees with respect to the tire equator CO, in this embodiment, one carcass 7a.

The turn-over portion 7B of the carcass 7 terminates at the bead portion 3 or the side wall portion 4 and has a tapered shape between the base portion 7A and the turn-up portion 7B outward from the bead core 2 in the tire radial direction. A stretchable bead apex 8 is provided to reinforce from the bead portion 3 to the sidewall portion 4 together with the folded portion 7B, and to increase the tire lateral rigidity.

As the carcass cord, an organic fiber cord such as nylon, rayon, polyester, aromatic polyamide or the like can be used in addition to a metal fiber cord such as steel as in the present embodiment. And the number of plies are set.

The belt layer 9 is formed of at least one belt ply 9a in which high-strength organic and inorganic belt cords are arranged at an angle of 0 to 70 degrees with respect to the tire equator. In the present example, the tread is formed from, for example, four belt plies 9a made of steel cord and has a width of 0.75 times or more the tread width and is arranged along the crown contour shape of the carcass 7. Part 5
Has a tag effect over substantially the entire width thereof.

The pneumatic tire 1 is a tubeless tire having a continuous inner liner layer 10 facing the tire cavity H inside the main body 7A of the carcass 7. In the present invention, the inner liner A thin sound absorbing layer 11 is interposed between the layer 10 and the carcass 7.

The inner liner layer 10 is made of a soft gas-tight rubber material having excellent gas impermeability such as butyl rubber and halogen rubber, and covers the front surface of the tire bore H to prevent leakage of the charged air. To prevent.

In this embodiment, the sound-absorbing layer 11 has a porous structure in which closed cells having an average cell diameter of 0.01 cm or less are dispersed almost uniformly inside a rubber-like base material of the same or different type as the inner liner layer 10. And is provided between the carcass 7 and the inner liner layer 10 and on the sidewall portion 4.

More specifically, the sound-absorbing layer 11 has at least a tire axial line L1 passing through the upper end of the flange of the regular rim R and a normal line L2 passing through the outer end of the tread portion 5 and orthogonal to the carcass 7. The area Y is continuously extended, and in this example, by tapering the both ends, stress concentration at the ends is reduced.

When the bubble diameter exceeds 0.01 cm or when the bubbles are continuous bubbles, the shrinkage of the sound absorbing layer 11 becomes excessive when the tire air is filled and when the tire is loaded, and the vibration of the carcass is absorbed.・ Insufficient mitigation effect.

Further, in order to obtain the necessary absorption / relaxation effect, it is necessary to further calculate (volume of bubble / apparent volume) × 100.
The porosity of the sound absorbing layer 11 expressed in (%) is preferably 20% or more, and the thickness t1 of the sound absorbing layer 11 is 2.0%.
mm or more is required. Note that excessively increasing the thickness t1 causes an increase in tire weight and a decrease in tire internal volume, and the like.
Therefore, the thickness t1 is generally set to 10 mm or less, preferably 7 mm or less.

Further, such a sound absorbing layer 11 is formed by kneading a foaming material such as dinitrone / pentamethylene / tetraamine, azodicarbonamide, azobisisobutyronitrile, toluenesulfonylhydrazide or the like in the base material. Using a porous base material, when forming a green tire, the porous base material is sandwiched between the carcass 6 and the inner liner layer 10 and integrally pressed together, while the foamed material is foamed by heating accompanying vulcanization molding. Thereby, it can be easily formed. In such a case, the pneumatic tire 1 of the present invention can be formed by substantially the same process operations as normal tire formation, and it is possible to improve production efficiency and reduce product cost. The sound absorbing layer 11 is made of a porous material that has been foamed in advance.
This porous material may be interposed between the carcass 6 and the inner liner layer 10 at the time of forming a green tire. , And for heavy-duty vehicles, passenger cars,
It can be used for various purposes such as for motorcycles and industrial vehicles.

[0023]

[Specific example] The structure shown in FIG.
A 3 / 80R20 tire was prototyped based on the specifications in Table 1, and the noise level of the prototype tire was measured and compared with a conventional tire.

[0024]

[Table 1]

FIG. 2 shows the comparison result at that time.

[0026]

As described above, since the tire of the present invention is provided with a sound absorbing layer between the carcass and the inner liner layer, the tire can effectively absorb and mitigate the vibration sound of the side wall portion and has an annular shape. The internal resonance can be reduced, and the noise of the tire can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of a tire showing one embodiment of the present invention.

FIG. 2 is a diagram showing a noise level of a tire of an example product together with a conventional tire.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bead core 3 Bead part 4 Side wall part 5 Tread part 7 Carcass 10 Inner liner layer 11 Sound absorption layer H Tire bore

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B60C 5/04 B60C 5/00 B60C 13/00 B60C 9/08

Claims (2)

(57) [Claims] 1. A carcass that is folded around a bead core of a bead portion from a tread portion to a sidewall portion and surrounds a tire cavity, and a carcass located inside the carcass and facing the tire cavity. An inner liner layer disposed, a sound absorbing layer disposed between the inner liner layer and the carcass and disposed on a sidewall portion, and the sound absorbing layer has closed cells having a bubble diameter of 0.01 cm or less. Pneumatic tire made of porous material. 2. The pneumatic tire according to claim 1, wherein the sound absorbing layer is disposed between the carcass and the inner liner layer when the tire is formed, and is foamed by vulcanization.